Undocumented? Unauthorized? Illegal? After 250 years, we're still debating what to call America’s visa-less immigrants.

By Jake Scobey-ThalJake Scobey-Thal is assistant managing editor at Foreign Policy. Previously, he worked as a freelance reporter in Myanmar and as the Asia Associate for Human Rights Watch. His articles have appeared in The Nation, Next City magazine, and Salon among others. He holds a bachelor's degree from the University of Pennsylvania.

U.S. policymakers and the country’s media erupted in a frenzy this summer over the issue of unaccompanied minors: Tens of thousands of youth from Central America, headlines proclaimed, will try to enter the United States in 2014 alone. But how to define these youth — drug mules and job stealers, or refugees fleeing gang wars and poverty — remains hotly contested. Consequently, there is little agreement on whether they should be allowed to stay in the United States or be sent home. Similar debates are happening in plenty of other countries, from Italy to Kenya to Australia. Yet the roots of dispute run particularly deep in the United States, which, due to centuries of economic success, has absorbed tens of millions of immigrants. Indeed, migrant youth are just the latest focus in an effort to legislate whom the United States lets cross its borders and whom it keeps at bay (or kicks out). Long before Latino children became an issue, U.S. leaders debated what to do with Chinese laborers, Eastern European radicals, even African slaves. In the process, the country played a pivotal role in defining the now-controversial term "illegal alien."

1765-1769

English jurist and politician William Blackstone publishes Commentaries on the Laws of England. A treatise on common law, it defines "aliens" — derived from the Latin term alienus, meaning "foreigner" or "outsider" — as people born outside the king’s "dominions," or territory over which the monarch rules (including the land that later became the United States).

1790

U.S. President George Washington approves the Naturalization Act, providing the first guidelines for granting national citizenship. The act limits naturalization to an "alien" who is a "free white person."

1798

In the aftermath of the French Revolution, which stoked fears of a similar event happening on U.S. shores, President John Adams signs the Alien and Sedition Acts. Among other things, the acts empower the president to expel "aliens" considered "dangerous to the peace and safety of the United States."

January 1, 1808

After decades of advocacy by abolitionists, a U.S. law makes it illegal to import new slaves into the country. (The domestic slave trade is left untouched.) According to historian Roger Daniels, "The approximately 50,000 slaves smuggled into the United States after 1808 became the first illegal immigrants."

1882

Congress passes the Chinese Exclusion Act, which imposes a 10-year freeze on Chinese labor migration in response to U.S. residents, particularly those on the West Coast, blaming immigrants for widespread unemployment and declining wages. Chinese immigrants, who worked in gold mines, garment factories, and railroad construction, had begun arriving in the United States en masse in the 1850s.

1916

Madison Grant, an American eugenicist and lawyer, publishes The Passing of the Great Race, which helps popularize pseudoscientific theories of racial superiority. Anti-immigration proponents use Grant’s theories to lobby for nationality-based restrictions on people coming into the United States. Scientist and historian Stephen Jay Gould has called the book the "most influential tract of American scientific racism."

1924

Following the post-World War I recession and amid mounting anti-immigration sentiment, the United States institutes a permanent quota system for entry into the country. No nationality can exceed what its population was in the United States in 1890, thereby giving preference to immigrants from Western and Northern Europe. The law allots visas, according to historian Mae Ngai, based on "a hierarchy of national and racial desirability."

July 28, 1951

The United Nations approves the Convention Relating to the Status of Refugees, which defines refugees, their rights, and the legal obligations a state has toward refugees within its borders. Many people previously classified as illegal immigrants, in the United States and elsewhere, now have claims to resettlement because they fear persecution in their home states. Yet countries remain conservative in granting refugee status: Today, according to the U.S. State Department, less than 1 percent of global refugees are resettled in a third country.

1965

Standing at the foot of the Statue of Liberty, President Lyndon B. Johnson signs the U.S. Immigration and Nationality Act, largely abolishing inequitable quota restrictions based on immigrants’ countries of origin. But it also restricts immigration from Western Hemispheric countries for the first time, effectively "creat[ing] illegal immigration from Mexico and Central America," according to Ngai.

1996

Fleeing violence and seeking economic opportunity, more than 4 million immigrants from Latin America, over half of them from Mexico, are in the United States illegally. In response, Congress passes legislation that expands border-control agencies, invests in fences in high-traffic areas, and increases penalties for aiding unauthorized immigrants.

October 1, 2004

The Minuteman Project, an informal group committed to patrolling the U.S.-Mexican border and preventing illegal entry, starts recruiting volunteers. The vigilantes are fed up with the failure of legislation to curtail unlawful border crossings: In 2004, an estimated 10.4 million unauthorized immigrants were in the United States.

September 2010

The Applied Research Center, now known as Race Forward: The Center for Racial Justice Innovation, launches the "Drop the I-Word" campaign. The effort urges media outlets, as well as the public, to stop describing immigrants as "illegal."

June 15, 2012

President Barack Obama announces that the United States will no longer deport young unauthorized immigrants who meet certain criteria. The individual must be no more than 30 years old, have come to the United States under age 16, and pose no threat to national security or public safety. The goal, Obama says, is to make immigration policy "more fair, more efficient, and more just."

April 2013

Facing pressure from immigration advocates, the Associated Press updates its stylebook so that it no longer sanctions phrases such as "illegal alien" or "illegal immigrant." According to the Associated Press’s senior vice president and executive editor, Kathleen Carroll, "‘illegal’ should describe only an action," not a person. (Prior to 2013, "illegal immigrant" was the preferred term to "illegal alien" or "undocumented worker.")

February 3, 2014

In a speech at Yale Law School, Supreme Court Justice Sonia Sotomayor explains her preference for using "undocumented immigrants" to describe foreign-born individuals entering the United States without permission. "To call them illegal aliens," she says, "seemed and does seem insulting to me."

July 8, 2014

Obama asks Congress to allocate nearly $4 billion to stem the influx of migrant youth from Central America. The money would fund increased surveillance, new detention facilities, and more immigration judges to expedite the processing of detainees. From October 2013 to June 15, 2014, some 52,000 unaccompanied children and teenagers were caught at the U.S.-Mexican border.

July 24, 2014

The New York Timesreports that the White House is considering a proposal to allow Honduran youths to apply to enter the United States as refugees. If approved, the effort would be the first to establish a U.S. refugee program for a country whose residents can reach U.S. borders by land. Similar programs have previously existed for countries, such as Vietnam and Somalia, experiencing humanitarian emergencies.